As known, traditional techniques for making pre-grouted panels made of mosaic tiles include a first step of laying tiles over a support base in a predetermined arrangement.
Particularly, the tiles are mutually offset in one or more predetermined directions to define a plurality of grooves.
Then, the grooves are filled with an appropriate resin, generally of thermoset type, having adequate flexibility to allow the panel to be also mounted to curved surfaces.
Typically, for proper tile positioning, a grid is used, which has a plurality of seats whose shape mates the shape of the tiles, and separated by a dual series of ribs designed to hold the tiles in spaced relation to define the grooves.
Then, the filling resin is directly poured onto the ribs, e.g. by suitable nozzles, and then cured to obtain the finished panel.
These prior art techniques still suffer from a number of recognized drawbacks, one of which consists in that excessive leakage of the jointing material always occurs in such processes.
This will require either provision of means for containing the filling material or removal of excess material.
A further drawback is that, in order to provide grooves of equal widths, the tiles are required to be locked in their position.
U.S. Pat. No. 3,335,048 and WO2005/092638 disclose methods for forming pre-grouted mosaic tile panels as described above, which include a further step in which a press is actuated to act upon the tiles.
Thus, the press will both allow containment of the filling material with the most uniform distribution, and locking of the tiles in their mutual positions.
WO2005/092638 provides a method of making pre-grouted panels in which a plurality of pneumatically operated pins are used, which press upon respective tiles to lock them in their preset position.
Nevertheless, these solutions have the drawback of not allowing simple control of the joint thicknesses, with negative effects on the aesthetic quality of the finished panel.
Furthermore, in addition to their complex and costly implementation, these prior art solutions have the additional drawback of forming joints having a flat and irregular top surface, which is of little aesthetic value.